Surinach Daniel, Rynes Mathew L, Saxena Kapil, Ko Eunsong, Redish A David, Kodandaramaiah Suhasa B
Department of Mechanical Engineering, University of Minnesota, Twin Cities.
Department of Biomedical Engineering, University of Minnesota, Twin Cities.
bioRxiv. 2023 Mar 28:2023.03.27.534480. doi: 10.1101/2023.03.27.534480.
Spatial navigation is a complex cognitive process that involves neural computations in distributed regions of the brain. Little is known about how cortical regions are coordinated when animals navigate novel spatial environments or how that coordination changes as environments become familiar. We recorded mesoscale calcium (Ca) dynamics across large swathes of the dorsal cortex in mice solving the Barnes maze, a 2D spatial navigation task where mice used random, serial, and spatial search strategies to navigate to the goal. Cortical dynamics exhibited patterns of repeated calcium activity with rapid and abrupt shifts between cortical activation patterns at sub-second time scales. We used a clustering algorithm to decompose the spatial patterns of cortical calcium activity in a low dimensional state space, identifying 7 states, each corresponding to a distinct spatial pattern of cortical activation, sufficient to describe the cortical dynamics across all the mice. When mice used serial or spatial search strategies to navigate to the goal, the frontal regions of the cortex were reliably activated for prolonged durations of time (> 1s) shortly after trial initiation. These frontal cortex activation events coincided with mice approaching the edge of the maze from the center and were preceded by temporal sequences of cortical activation patterns that were distinct for serial and spatial search strategies. In serial search trials, frontal cortex activation events were preceded by activation of the posterior regions of the cortex followed by lateral activation of one hemisphere. In spatial search trials, frontal cortical events were preceded by activation of posterior regions of the cortex followed by broad activation of the lateral regions of the cortex. Our results delineated cortical components that differentiate goal- and non-goal oriented spatial navigation strategies.
空间导航是一个复杂的认知过程，涉及大脑分布式区域的神经计算。对于动物在新的空间环境中导航时皮质区域是如何协调的，或者随着环境变得熟悉这种协调如何变化，我们知之甚少。我们记录了小鼠在解决巴恩斯迷宫任务时背侧皮质大片区域的中尺度钙（Ca）动态，巴恩斯迷宫是一项二维空间导航任务，小鼠使用随机、序列和空间搜索策略导航到目标。皮质动态表现出重复的钙活动模式，在亚秒时间尺度上皮质激活模式之间有快速而突然的转变。我们使用聚类算法在低维状态空间中分解皮质钙活动的空间模式，识别出7种状态，每种状态对应一种独特的皮质激活空间模式，足以描述所有小鼠的皮质动态。当小鼠使用序列或空间搜索策略导航到目标时，在试验开始后不久，皮质的额叶区域会持续较长时间（>1秒）可靠地被激活。这些额叶皮质激活事件与小鼠从迷宫中心接近边缘的过程同时发生，并且在其之前有一系列皮质激活模式的时间序列，这些序列对于序列和空间搜索策略是不同的。在序列搜索试验中，额叶皮质激活事件之前是皮质后部区域的激活，随后是一个半球的外侧激活。在空间搜索试验中，额叶皮质事件之前是皮质后部区域的激活，随后是皮质外侧区域的广泛激活。我们的结果描绘了区分目标导向和非目标导向空间导航策略的皮质成分。
